Krivan H. C. et al (1989 J. Biol. Chem) reported that M. pneumoniae binds avidly to sulphatides. A membrane preparation M. pneumoniae was applied to a dextran sulphate affinity column, and two proteins of 52 kDa and 32 kDa molecular weight bound to the column (Geary S. et al. 1990, IOM Abst.). The 52 kDa protein can be detected in western blots of membrane preparations from M. pneumonie using the monoclonal antibody (Ab) CP3-46F5 (F5) (Chandler et al. 1989. Infect. Immun. 57:1131-1136). Chromosomal DNA from M. pneumoniae M129 was restricted and ligated to the phagemid vector Bluscript (Stratagene). Escherichia coli XL1-Blue colonies expressing epitopes of the 52 kDa protein were detected immunologically by reaction with monoclonal antibody CPs-46F5. Three positive phagemid constructs were identified. They code for peptides that are smaller than the size expected for fusion protein on western blots. The sequenc of the cloned Mycoplasma DNA inserts is being analyzed to determine the presence of UGA condons. UGA condon code for tryptophan in Mycoplasma spp., but shen cloned into E. coli result in production of truncated proteins. Surface proteolysis of strain M129 indicated the surface exposed nature of the protein. Monoclonal antibody F5 was purified from ascites fluid in order to affinity purify the protein on an Ab affinity column. Location of the 52 kDa protein on M. pneumoniae will be studied by immune electron microscopy. Localization of the protein at the adherence tip structure would indicated the importance of the protein in adherence. The role this protein plays in the adherence of M. pneumoniae will be evaluated in adherence inhibition studies.